Building the Fuel Pumps and Naviflow

TLDR

• Assembled Naviflow (without final torque)
• Test fitted Rotax Fuel Pump but ran into problems

Details

I took a bunch of parts related to fuel lines from the hangar back to my garage so I can make some progress at home.

I focused on building the fuel pumps and finsihing up the Naviflow unit.

Naviflow

The work on this one stalled for a while because I was waiting on the FWF kit previously, and when it arrived it didn’t have the check valve, so I had it on the backorder with Sling.

I’ve finally received all the parts and finished the window work, so I am ready to finish building the naviflow and put it onto the firewall. I’m quite excited about this :-D

So the instruction is a little hard to find as it didn’t come with and written document. But Henry (the co-owner of the aerospace innovations) did a good job publishing a series of detailed videos walking through the process.

The work I really needed to do is just connecting the rubber hoses and install the checkvalve, then torque the two ends filter. The torquing should be done on the airplane to ensure the unit is straight and flat, so I skipped this step for now.

The rubber hoses are slightly too long, by just a few millimeters. I used a craft knife to shave off the extra length, and added 2 ear clamps before connecting the checkvalve and the naviflow unit itself.

Fuel Pump

Testing fitting the pumps gave me a lot of trobule compared to the Naviflow.

So, the picture above is one half of the entire asembly, the other half is symetric. When I test fit the parts on this half, 3 problems came up:

1. The outter loop is much too short than the inner loop. The fittings doesn’t even reach each other.

2. The M14 bolt threads into the pump with almost no friction. The instruction didn’t call for any crush washer, but I feel like the instruction might be wrong as I don’t see how this part will seal without something extra there.

3. Tht other end of the pump: the instruction calls for 1/8 NPT with 2 washers. It also doesn’t make sense to me because I’ve never seen NPT fittings and washers used together, and also the threads are way too long, I am not sure washers will be sufficiently crushed even if I use them. The rotax service instruction says to use M10 fitting here. So it seems there is a fundamental difference between thread standards between sling’s KAI and Rotax.

I am sending the question to Sling. To be updated soon, hopefully.